1. Field of the Invention
The present invention is directed to the field of high speed sequential switching of high voltage discharge current from a common supply to a plurality of individual output terminals. More specifically, the present invention is directed to an improved miniaturized distributor, such as the type employed in automotive ignition systems, which overcomes problems of arc-over by employing a fluid medium having a relatively high dielectric constant surrounding the contact areas.
2. Description of the Prior Art
As internal combustion engines were developed to use higher ignition spark energy, in the range of 40,000 volts, over longer burn times, it was found that high voltage arc-over sometimes occurred between the rotor contact and a plurality of adjacent spark plug contacts in conventional distributors having air dielectrics. For instance, if the rotor contact was not in proper registration with the selected spark plug contact at the time high voltage was applied to the rotor contact, dielectric breakdown would occur and result in conduction between the rotor contact and the wrong spark plug contact, thereby causing engine misfire.
Development of a distributor, such as that shown in U.S. Pat. No. 3,799,135, was made, in which erroneous discharge was eliminated by providing a multi-legged spider-type high voltage conductor in arc-gap relationship with corresponding spark plug contacts separated by a rotating element. The rotating element was constructed of a solid insulating material with an air dielectric window formed therethrough. As the element was rotating, the window allowed arc-gap conduction between the corresponding spider leg and spark plug contact, while the solid insulating material, having a high dielectric constant, prevented simultaneous discharge-conduction to other spark plug contacts.
Additional progress in electronic ignition controls, such as that disclosed in commonly assigned U.S. Pat. No. 3,969,614, led to the invention of a new type distributor disclosed and claimed in commonly assigned U.S. patent application No. 803,197, filed June 3, 1977 now U.S. Pat. No. 4,153,030. That air dielectric distributor invention eliminated conventional vacuum and centrifugal advance mechanisms by providing wide angles of registration between a conductive rotor element and respective spark plug contacts. The invention also eliminated the need to increase the diameter of the distributor, in order to provide a large air dielectric spacing between the conducting contacts, by arranging the contacts in a plurality of stacked sets separated sufficiently to eliminate erroneous arc-over.